HYDRONICS | FOLEY | CONTINUED FROM PAGE 30
serves as a backup in the event of a component failure in the radiant system. Cooling is provided using Carrier unitary equipment. A central chiller plant was considered, but space, noise and billing issues shelved this idea. Fresh air is ducted into each unit through an Aaon make-up air unit, which brings in 1,800 cfm of fresh air while filtering and conditioning (heating/cooling/de-humidification) the air, depending on ambient conditions. Common areas such as the lobby, hallways and elevator lobby are conditioned by a gas pack rooftop unit. A back stairwell and a common area exercise room are conditioned by Mitsubishi ductless split units. The heart of the mechanical system was the boiler plant:
Two Lochinvar Knight XL condensing gas boilers. The two boilers are staged with a tekmar staging/reset control. The boilers supply two 120-gal., indirect DHW tanks, radiant zones, hot deck coils on the air handlers and snowmelt for the parking ramp and public walkways. Snowmelt is automatically controlled by a tekmar 661 snow/ice detection control. A timer switch allows for manual activation of the system. The radiant supply water is mixed down using Wirsbo Pro Mix 101 controls tied to Belimo 3- way floating action motorized valves. The underground parking garage was ventilated with two
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7,500 cfm exhaust fans with a fresh air louver at the opposite end of the garage. A Macurco CO monitor and switch activates the fans if ambient CO in the garage rises
above 25 ppm. In addition, a timer runs the fans for 10 minutes every hour, regardless of CO level, to flush out stale air and bring in fresh air. One of the biggest challenges on this project was logistics.
With no parking, difficult deliveries and limited staging area, poor planning would have been costly. I learned quickly to plan ahead, coordinate deliveries and arrive at the site early. We were able to use the underground garage for a while, but my bigger work trucks would not fit in the garage. I had budgeted $2,000 for parking tickets on this job, but we have already racked up over $5,000 in tickets, and we are just starting the rowhouses. This has to be factored in when pricing the job. You are not going to do a commercial project in Georgetown and not get tickets. This condominium project has been operational since late
2009. The six rowhouses are going up at this writing. Commercial jobs lend unique challenges to mechanical projects that require unique solutions. Our commercial project base is growing, and we have several more in progress. Don’t be afraid to jump in and try a commercial project, but make sure that you are adequately prepared and are ready for tight schedules and hard work. I will detail the logistics getting, designing, planning and
installing large residential and commercial projects in future columns. More information on the Wormley Row project can be found at these links:
www.wormleyrow.com/,
http://bit.ly/r96tIf, and
http://bit.ly/oxaHEy. l
e Circle 25 on reader reply form on page 96
phc august 2011
www.phcnews.com
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